不同施肥水平下黍子根系对干旱胁迫的反应

不同施肥水平下黍子根系对干旱胁迫的生物学响应研究表明，无论施肥与否，拔节期或抽穗期干旱胁迫均会使黍子根重、根长、根活力、次生根数、根系SOD活性及株高与地上部干重明显降低，MDA含量明显增高；水分胁迫解除后，黍子根系增长迅速，表现出明显的补偿效应和根系对水分反应敏感的特点，但干旱造成的不利影响在后期未能完全补偿。抽穗期干旱胁迫对黍子的影响大于拔节期，这是由于拔节期胁迫后恢复水分供应，根系有较长的时间与空间进行补偿的结果。通过施肥改善土壤肥力，可以肥促根、以肥调水、提高土壤水分利用效率和增加产量，在一定程度上缓解干旱胁迫的影响。     

不同氮营养水平对水葫芦根系活力的影响

[目的]研究水葫芦(Eichhornia crassipes)根系活力与水体中氮浓度的关系。[方法]以不同氮营养水平培养水葫芦,研究水体中氮浓度对水葫芦根系活力的影响。[结果]氮浓度对水葫芦根系有较大的影响,在适宜的氮浓度水环境中水葫芦生长良好,并且根系活力和根系过氧化物酶活性都比较高。其中3.5 mg/L氮水平处理的水葫芦根系活力和根系过氧化物酶活性达到最高,过高的氮水平不但抑制水葫芦的根系活力,同时也抑制水葫芦根系的过氧化物酶活性。[结论]不同氮营养水平不仅影响水葫芦的根系活力,而且对根系过氧化物酶的活性也有明显影响。     

Tyrosinase inhibition constituents from the roots of Morus australis

The phytochemical profiles of Morus australis roots, stems and twigs were firstly compared by HPLC analysis. It was found that Morus australis stem extract mainly contained one known tyrosinase inhibitor, oxyresveratrol, while its root and twig extract might contain some unknown potential tyrosinase inhibitors. The root extract of Morus australis was further investigated in this study. One new compound, austraone A, together with 21 known compounds, was isolated and their structures were identified by interpretation of MS and NMR data. In the tyrosinase inhibitory testing, some of them, such as oxyresveratrol, moracenin D, sanggenon T, and kuwanon O, exhibited stronger tyrosinase inhibitory activities than that of kojic acid. These results suggested the Morus australis root extract as a good source of natural tyrosinase inhibitors with a great potential to be used in foods as anti-browning agents and in cosmetics as skin-whitening agents.     

Changes in forest-floor chemistry caused by a birch admixture in Norway spruce stands

The aim of this study was to determine how soil chemistry and the distribution of fine roots (<1 mm) in the organic and upper mineral soil horizons were affected by an admixture of birch (Betula pendula Roth and B. pubescens Ehrh.) in Norway spruce (Picea abies (L.) Karst) stands. The surface organic horizons (LF and H) and mineral soil were characterized to a depth of 10 cm on three sites in southern and central Sweden. On these sites, replicated plots had been established that contained either ca. 30-year-old birch growing as a shelter over similar-aged spruce (mixed plots) or spruce only. The treatments had been created 8–11 years before this study was done. A fourth site, with plots containing ca. 90-year-old spruce or birch/spruce, and a fifth site, with 30-year-old spruce and a low admixture (12% by basal area) of birch, were also included in the study. Concentrations of Ca and Mg and pH in the LF layer were significantly higher in plots with a birch admixture. In the H-horizon, concentrations of K, Ca and Mg were significantly higher in mixed plots than in plots with pure spruce. Consequently, base saturation was higher in mixed plots than in pure spruce plots. A shelter of birch decreased the total amount of spruce fine roots (<1 mm), as revealed at one of the sites. Total fine root biomass (birch + spruce) in the organic and mineral soil horizons (to 10 cm) did not differ significantly between the pure spruce stands and the spruce stands with a birch shelter.     

利用多因子正交试验建立桑的无菌快繁体系

以桑侧枝茎段为材料,利用L9(34)正交设计探讨培养基种类和激素配比对桑茎段丛生芽诱导效率的影响,并对影响桑外植体生根的主要因子进行了研究.结果表明:A2B2C1为诱导出芽的最佳培养基与激素组合,并且可同时实现芽增殖;生根培养基为WPM+1.0 mg/L IBA.     

杜松根系观察及切根试验的研究

文章通过对杜松根系的观察与系统研究分析 ,对杜松根系在土壤中的分布情况进行观察。通过杜松切根试验 ,了解杜松在移植过程中 ,根系受损及恢复状况 ,为提高杜松移植成活率 ,提供科学依据。     

外源ABA对渗透胁迫下玉米幼苗根系渗透调节的影响

用ABA处理不同抗旱性的两个玉米品种幼苗根系, 测定了根系的水势、渗透势、渗透调节能力及4种渗透调节物质的变化, 结果表明: 渗透胁迫条件下, ABA能提高根系的水势、降低渗透势、增加渗透调节能力, 且对抗旱性强的鲁玉14号的作用大于抗旱性弱的掖单13号. 正常供水条件下, ABA处理对根系水势的提高有一定的作用, 但对渗透势及     

甘薯根系发育对干旱胁迫的响应及化控对其缓解作用研究综述

本文综述了干旱胁迫下甘薯根系对干旱胁迫的响应、化学调控对甘薯根系生长发育及其对缓解干旱胁迫的影响,以期为提高甘薯产量潜力、完善轻简化栽培技术提供理论和技术借鉴。     

水稻根系性状与地上部的相关及根系性状的遗传研究

 为开展水稻根系性状的育种提供理论依据和选择指标，本文对12个不同穗型水稻品种的根系形态特征与地上部关系及根系性状的遗传进行了研究。结果表明：根数、根重和根直径分别与地上部有关性状相关显著，可作为水稻育种中的根系选择指标。遗传分析显示，上述3个根系性状均为数量遗传，与细胞质基因无关。3个根系性状的遗传变异中，加性、显性和上位性都很重要。     

麦棉两熟复合根系群体对棉花根际非根际土壤酶活性和土壤养分的影响

 在麦棉两熟双高产条件下，设置麦棉自然根系（根系和肥水均可相互通过）、麦棉纱网隔根（肥水可相互通过，根系不能相互通过）和麦棉塑膜隔根（根系和肥水均不能相互通过）3种套种复合根系群体，研究麦棉两熟复合根系对棉花根际和非根际土壤酶活性和土壤养分的影响。结果表明，在麦棉共生期，与麦棉塑膜隔根相比，麦棉自然根系和纱网隔根复合群体中棉花根际非根际土壤脲酶、蔗糖酶和蛋白酶的活性均有所提高，其中以麦棉纱网隔根处理的土壤酶活性最高。同时，麦棉自然根系复合群体中棉花根际非根际土壤的养分含量降低，纱网隔根处理减缓了小麦根系对棉花根系营养的竞争，同时又可能是小麦根系分泌物的作用使其养分含量最高。到棉花盛蕾期，小麦已收获，麦棉复合群体根际和非根际土壤酶活性和土壤养分状况均得到不同程度改善，其中以麦棉自然根系复合群体的改善程度最大,其土壤脲酶和蔗糖酶的活性达到最高，土壤有机质和全氮含量超过塑膜隔根，但仍低于纱网隔根。麦棉套作地下部不仅存在小麦对棉花营养竞争的不利一面，同时还存在小麦根系促进棉花根际非根际土壤酶活性和土壤养分含量提高的有利一面，且此效应将持续影响套作棉花一生。